Abstract: Dimensioning is a fundamental aspect of engineering drawings that communicates the size, shape, and location of features in manufactured components. Accurate dimensioning ensures proper fit, function, and interchangeability of parts. This research investigates traditional and modern dimensioning techniques used in 2D and 3D engineering drawings. It evaluates their impact on design clarity, manufacturability, tolerance control, and standard compliance. By reviewing global standards like ASME Y14.5 and ISO 129-1, comparing manual vs. CAD-based dimensioning, and analyzing industry practices, the paper identifies best practices and common challenges. The findings aim to guide engineering students, draftsmen, and design engineers in adopting effective and standardized dimensioning methods. Keywords: Dimensioning, Engineering Drawing, Linear Dimensioning, GD&T, ISO 129, ASME Y14.5, CAD Drafting, Tolerancing, Technical Communication, Manufacturing Accuracy.